Tag Archives: muscle

The next innovative material for clothes? How about muscles

We wear clothes made from unusual things all the time — you even start to wonder what a “normal” material would be. From plant fibers to plastic to stuff produced by worms, there’s no shortage of raw materials that can be used to make clothes. But researchers are constantly looking for others, with potentially even better properties.

An unusual idea is muscles — or muscle fibers, to be more precise. It sounds a bit odd, but according to a new study, it could be more resilient than Kevlar, at a price that is competitive with other materials? Oh, and it’s also more eco-friendly, and no animals are harmed in the process.

Would you wear clothes made from synthetic muscle protein? Image credit: Washington University in St. Louis.

Cheap, durable, scalable

A belt made from muscle sounds like something straight out of a horror movie, but thanks to the work of researchers at Washington University in St. Louis, it may become real in the not too distant future. The team used microbes to polymerize proteins which were then spun into fibers (somewhat like how silkworms produce silk, but using microbes instead of worms).

The microbes can be engineered to tweak the properties of the protein, and in this case, researchers designed fibers that can endure a lot of energy before breaking.

“Its production can be cheap and scalable. It may enable many applications that people had previously thought about, but with natural muscle fibers,” said Fuzhong Zhang, professor in the Department of Energy, Environmental & Chemical Engineering, and one of the study authors.

No actual animal tissues are needed for the process. Instead, the process starts from a protein called titin, which grants muscles passive elasticity. Adult humans have about 0.5 kg of titin in their bodies.

Titin was desirable because of its molecular size. “It’s the largest known protein in nature,” said Cameron Sargent, a Ph.D. student in the Division of Biological and Biomedical Sciences and a first author on the paper. This makes it very resilient but raises some challenges in producing it.

Surprisingly doable

As weird as it may sound, the idea is not new. In fact, researchers have been toying with the idea of using muscle protein as fibers for a long time — but gathering them from animals is unethical and challenging in many ways. So they looked for another idea.

“We wondered, ‘Why don’t we just directly make synthetic muscles?'” Zhang said. “But we’re not going to harvest them from animals, we’ll use microbes to do it.”

Getting bacteria to produce large proteins is very hard. So instead, the researchers engineered bacteria to piece together smaller parts of the protein into an ultra-sturdy structure. They ended up with a protein with a high molecular weight and about 50 times larger than the average bacterial protein. Then, they used a wet-spinning process, converting the proteins into fibers about 10 times thinner than a human hair.

They opted for a fiber that is especially strong, but the process could be tweaked for any desired property. You could make clothes that are softer or dry quicker, the process can be scaled in any desired direction.

“The beauty of the system is that it’s really a platform that can be applied anywhere,” Sargent said. “We can take proteins from different natural contexts, then put them into this platform for polymerization and create larger, longer proteins for various material applications with a greater sustainability.”

Furthermore, because the fibers are almost indistinguishable from natural muscle, they can also be used in medical procedures, for instance for sutures and stitching up wounds. Unlike other synthetic polymers, this is also biodegradable and less polluting to the environment.

“By harnessing the biosynthetic power of microbes, this work has produced a novel high-performance material that recaptures not only the most desirable mechanical properties of natural muscle fibers (i.e., high damping capacity and rapid mechanical recovery) but also high strength and toughness, higher even than that of many manmade and natural high-performance fiber,” the researchers conclude.

So, would you wear clothes made from muscle?

The research has been published in Nature Communications.

Credit: Pixabay.

Bedtime protein shakes might lead to more muscle gain than daytime protein without adding fat or harming sleep

Studies suggest that ingesting protein just before overnight sleep improves muscle gains in response to resistance training. However, does the timing of the protein intake really matter that much? Seems so, according to a new review of recent studies which found that overnight sleep is a unique nutritional window for boosting muscle gains.

Credit: Pixabay.

Credit: Pixabay.

The review was led by Dr. Tim Snijders, Assistant Professor at Maastricht University. In 2015, Snijders and colleagues performed their own investigation of muscle gain from nightly protein intake. Their study involved 44 healthy young men on a 12-week lifting program, half of whom were given a pre-sleep protein shake consisting of 30g of casein and 15 grams of carbs, while the other half received an energy-free drink. Both groups grew bigger quads and could lift more but the protein-before-bed group saw better gains in both muscle strength and size.

Snijders’ study begged the question: is the timing of the protein shake before bed important or is it all just about the higher intake of protein and calories? That is difficult to show directly because “a huge number of participants would be needed to prove whether a difference might exist in response to pre-sleep protein, versus protein intake at other times of the day,” explained Snijders.

However, this most recent review of relevant scientific literature suggests that there are numerous indirect indicators that pre-sleep protein is specifically important for muscle gain, with sleep playing a unique window of opportunity.

When muscles suffer trauma from resistance training, this disruption activates satellite cells located on the outside of muscle fibers to proliferate at the injury site. These cells perform the biological function of repairing or replacing damaged muscle fibers, often leading to an increase in muscle fiber cross-sectional area (hypertrophy). In order to sustain hypertrophy, muscle cells need amino acids from protein present in the blood. However, the body does not release amino acids at near-constant circulating levels. Rather, they fluctuate in peaks and valleys depending on the amount of ingested protein.

“A survey of over 500 athletes found they were typically consuming at total of more than 1.2g protein per kilo of bodyweight across three main meals, but only a paltry 7g of protein as an evening snack. As a result, lower levels of amino acids would be available for muscle growth during overnight sleep,” Snijders commented on the results of one of the studies included in his review.

Evidence suggests that pre-sleep protein intake allows muscles to absorb more amino acids at night — and this doesn’t mean that there will be less during the day.

“The muscle-building effects of protein supplementation at each meal seem to be additive. In one study we found that the consumption of ample amounts of protein (60g whey) before overnight sleep did not alter the muscle protein synthetic response to a high-protein breakfast the following morning,” Snijders said.

“What’s more, others have shown that adding a protein supplement at bedtime does not affect appetite the following morning – so it is unlikely to compromise total protein or calorie intake.”

Bedtime protein doesn’t seem to make you fat either. Surprisingly, it might have the opposite effect by speeding up metabolism. In one study, researchers compared an 8-week morning vs evening casein program and found no difference in fat mass between the two programs.

“Supporting this, another group found in 11 young active men that a pre-sleep casein shake actually increased the rate of fat burning the following day. This might be because casein ingestion reduces the insulin response to subsequent meals, which pushes your body to use more fat,” Snijders said.

The review also found that bedtime protein doesn’t interfere with sleep quality or drive onset latency.

“In conclusion, protein ingestion prior to sleep is an effective interventional strategy to increase muscle protein synthesis rates during overnight sleep and can be applied to support the skeletal muscle adaptive response to resistance-type exercise training,” the authors concluded.

The findings appeared in the journal Frontiers in Nutrition

Study proves muscle memory happens on a genetic level

A new study has found that muscles “remember” how they grow.

It happens all the time. You press your ATM code without even thinking about it. You can’t remember the chords to a song, but your hands just play it anyway. You haven’t played sports since forever, but somehow, your body still remembers how it’s done. We call it muscle memory, but we don’t really know what muscle memory is.

Muscle memory is a type of motor learning, a type of procedural memory that involves consolidating a certain task (consciously or unconsciously) until you can do it almost automatically. Sometimes, muscle memory feels like the body is working without you. But it’s not just about actively doing things. Now, for the first time, a study has proven that human muscles also possess a ‘memory’ of earlier growth, and this process happens at the DNA level.

Using DNA testing techniques, British researchers studied over 850,000 sites on human DNA, finding that some genes are marked with chemical tags when muscle grows following exercise. This is called an epigenetic change — something that’s not directly affecting the DNA strands, but rather tells genes when to be active and when to be inactive. So basically, what these epigenetic changes do is tell the DNA how to act without changing the DNA itself.

Study authors Dr. Adam Sharples and Robert Seaborne, his PhD student, explain:

“In this study, we’ve demonstrated the genes in muscle become more untagged with this epigenetic information when it grows following exercise in earlier life, importantly these genes remain untagged even when we lose muscle again, but this untagging helps ‘switch’ the gene on to a greater extent and is associated with greater muscle growth in response to exercise in later life – demonstrating an epigenetic memory of earlier life muscle growth!”

This could have significant implications for athletes, but also regular people recovering from a muscle injury. It could even help people train better, especially when they want to grow their muscles.

For athletes, it could mean that one- or two-year bans for using muscle-growing pills are simply not long enough. Because the effects are long-term, the ban should also be long-term, researchers suggest.

“If an elite athlete takes performance-enhancing drugs to put on muscle bulk, their muscle may retain a memory of this prior muscle growth. If the athlete is caught and given a ban – it may be the case that short bans are not adequate, as they may continue to be at an advantage over their competitors because they have taken drugs earlier in life, despite not taking drugs anymore. More research using drugs to build muscle, rather than exercise used in the present study, is required to confirm this.”

Journal Reference: Robert Seaborne et al. Human Skeletal Muscle Possesses an Epigenetic Memory of Hypertrophy. doi:10.1038/s41598-018-20287-3

muscle

Scientists grow functioning human muscles from skin cells

muscle

Credit: Pixabay.

In a novel research project, bioengineers at Duke University demonstrated how to grow functioning human muscles from induced pluripotent stem cells. It’s the first time scientists have shown that it’s possible to grow human muscles essentially starting from scratch, all by coaxing skin cells to generate stem cells, which ultimately turned into muscle tissue.

Previously, the same team grew functioning human muscle — the kind that contracts in response to a stimulus such as an electrical signal — in culture, starting with pea-sized globs of muscle, sourced from human volunteers.

While the previous attempts grew new muscle from native muscle, the present work is far more sophisticated since the resulting tissue doesn’t depend on donated muscle. What’s more, the ability to generate muscles starting from non-muscle tissue helps scientists grow far more of these cells. Bearing this in mind, the new technique will prove far more useful as far as genome editing and cellular therapies go. It also makes it possible to tailor custom treatments for rare muscle disorders such as muscular dystrophies or test substances for new drug discovery.

Skin to muscle

Researchers have grown the first functioning human muscle tissue from skin cells reprogrammed into stem cells. Credit: Duke University.

Researchers have grown the first functioning human muscle tissue from skin cells reprogrammed into stem cells. Credit: Duke University.

It all starts from human induced pluripotent stem cells (iPSCs), which are adult non-muscle tissues, such as skin or blood, that have been reprogrammed to revert to a primordial state. Just like any stem cells, iPSCs can then be programmed to differentiate into any kind of tissue. In our case, scientists flood the iPSCs with a signaling molecule called Pax7 which triggers muscle formation out of the cells.

“Starting with pluripotent stem cells that are not muscle cells, but can become all existing cells in our body, allows us to grow an unlimited number of myogenic progenitor cells,” explained Nenad Bursac, professor of biomedical engineering at Duke University. “These progenitor cells resemble adult muscle stem cells called ‘satellite cells’ that can theoretically grow an entire muscle starting from a single cell.”

It sounds easy enough when reading this but the truth is it took Bursac and colleagues years of trial and error before they got it just right. One important breakthrough that enabled cell proliferation into functioning skeletal muscle was the introduction of a unique cell culture conditions and 3-D matrix, rather than having to rely on the 2-D culture approaches that are typically used. This way, cells can grow and develop much faster and longer.

Once the cells reached a critical threshold, the scientists stopped the flow of Pax7 and started giving the cells the support and nourishment they needed to fully mature.

After two to four weeks of 3-D culture, the muscle cells aggregated into muscle fibers that can contract and react to electrical pulses and biochemical signals just like natural muscles would in response to neuronal inputs.

The lab-grown muscle fibers were put to the test when they were implanted into adult mice. Small ‘windows’ grafted on the backs of the mice allowed the researchers to observe how the muscles they’ve grown behaved inside the rodents. The muscles survived and functioned for at least three weeks, during which it progressively integrated with native tissue through vascularization.

The resulting muscle, unfortunately, is not nearly as strong as native muscle tissue nor that grown from muscle biopsies for that matter. It makes up for it, however, in versatility and the ability to grow many more cels from a smaller starting batch than other methods, such as the biopsy one. What’s more, the team’s new muscle seems capable of supplying a special reservoir of cells that muscles can use to regenerate themselves following injury or exercise — an important hallmark of natural muscle. Biopsied muscle tissue, in contrast, produces a far less richer reservoir.

“The prospect of studying rare diseases is especially exciting for us,” said Bursac. “When a child’s muscles are already withering away from something like Duchenne muscular dystrophy, it would not be ethical to take muscle samples from them and do further damage. But with this technique, we can just take a small sample of non-muscle tissue, like skin or blood, revert the obtained cells to a pluripotent state, and eventually grow an endless amount of functioning muscle fibers to test.”

Findings appeared in the journal Nature Communications

Prehistoric women had strong, bulky arms — more powerful than today’s athletes

Ancient women farmers were about as strong as today’s elite rowers, thanks to intensive manual labor.

Manual labor made ancient women impressively strong, new study reports. Credits: Victoria Garcia.

Manual agriculture was never easy, especially before the plow was invented. You need to till the soil, plant crops, harvest crops, and grind the grain to make flour — all by hand, using only digging sticks and rudimentary flint sickles inserted into wooden handles. As a result, ancient people would have likely been quite buffed compared to us. This theory has been confirmed several times through bone analysis, but most studies have focused on male limbs. Now, a comprehensive study on female limbs (the first one of its kind) confirms a similar trend, with an even more striking difference: women living during the first 5,500 years of farming in Central Europe had some serious upper body strength.

During a lifetime, bones twitch and turn, they support lifting, pulling and running. They can tell a lot about a person’s physical capabilities and overall lifestyle. In a way, woman bones are even more telling because they also store minerals to be used during pregnancy and lactation.

Alison Macintosh, who studies skeletal biomechanics at the University of Cambridge’s anthropology department, says that this extra complexity is part of the reason why woman bones have been so understudied.

“There has been little work done yet, and what does exist has focused on men largely because the relationship between behavior and bone is a bit less complex in men than in women,” Macintosh said.

Example of a bone model. Credits: Fred Lewsey / Cambridge University.

So she and her colleagues used a 3D laser imaging system to analyze and create models of 89 shinbones and 78 upper arm bones from women who lived during the Neolithic (5300 B.C.E.–4600 B.C.E.), Bronze Age (3200 B.C.E.–1450 B.C.E.), Iron Age (850 B.C.E.–100 C.E.), and Medieval (800 C.E.–850 C.E.) periods in Central Europe. In order to have a frame of reference, they also recruited dozens of female Cambridge students, both athletes (accomplished runners, soccer players, and rowers) and non-athletes. From the living women, they used CT imaging to picture the bones. “We can then quantify bone strength using special software,” Macintosh explains.

By analyzing bones in this way, researchers can then infer how strong the arms and legs are. They found that Neolithic women had impressively strong limbs. Women’s leg strength was surprisingly variable, encompassing the entire range which was seen in the living women — from sedentary women through to ultramarathon runners. When it came to arms though, it was a completely different story. Ancient women had extremely strong arms, with bones about 16 percent larger than those of competitive rowers (which routinely row over 100 km/week) and 30 percent larger than recreationally active women.

“This suggests that prehistoric agricultural women were doing a huge range of daily activities that involved varying amounts of strain on their legs, but were consistently doing higher levels of manual labor than living rowers,” Macintosh continues.

It also means that anthropologists have been greatly underestimating the muscular load that agricultural tasks require, as well as the women’s engagement in such tasks.

“Prior to the invention of the plough, subsistence farming involved manually planting, tilling and harvesting all crops,” said Macintosh. “Women were also likely to have been fetching food and water for domestic livestock, processing milk and meat, and converting hides and wool into textiles.

Women in later times also had strong arms. As technology advanced though, women were spared of some of this backbreaking work. As a result, the muscular strength started to drop bit by bit.

“In the Neolithic and Bronze Age periods, grain was processed using a saddle quern, which is a time-consuming and relatively inefficient way to grind grain. In the Late Iron Age, a new grain grinding technology, the rotary quern, became common in Central Europe. This technology is more efficient, takes less time, and uses less muscle activity to grind the same amount of grain as a saddle quern. This may be one of the main reasons why women’s upper limb bone strength starts to decline between the Iron Age and the Medieval period in this region of Europe.”

It’s important to note that women played a crucial role during this early part of mankind’s development. We don’t really know how chores were divided between men and women. In fact, the complexity of this division might make it hard to track specific bone signatures.

“The variation in bone loading found in prehistoric women suggests that a wide range of behaviours were occurring during early agriculture. In fact, we believe it may be the wide variety of women’s work that in part makes it so difficult to identify signatures of any one specific behaviour from their bones,” Macintosh concludes.

In the future, Macintosh and colleagues want to study how the nutritional changes which followed the agricultural revolution affected the lifestyle (and bones) of early humans.

Journal Reference: Alison A. Macintosh, Ron Pinhasi, and Jay T. Stock. Prehistoric women’s manual labor exceeded that of athletes through the first 5500 years of farming in Central Europe. DOI: 10.1126/sciadv.aao3893

Muscle-like fabric could turn regular clothes into ‘Superman suits’

What a textile exoskeleton might look like. The muscle-like fibers made by Swedish researchers is shown here in black. Credit: Thor Balkhed/Linköping University

These muscle-like textiles made from cellulose yarn can respond to low-voltage electricity to contract just like actual muscle fibers. Clothing made from such a material could help those with disabilities enhance their mobility by providing a far more light-weight alternative to cumbersome exoskeletons. It could also help otherwise healthy people who have physically intensive jobs lessen their load.

“Like a muscle, the actuation is triggered by an electrical potential, driven by a chemical reaction, and operated in an electrolyte,” says study author Edwin Jager, an applied physicist at Linköping University, Sweden.

The fabric was first knitted and woven so it matched the structure of real muscle. It was then bathed in an electroactive solution to make it responsive to electricity. This rather simple recipe allows the fabric to exhibit properties similar to biological muscle, as reported in Science Advances.

The knitted textile offers flexibility while the woven version can exert more force since, like real muscle, woven fibers are coupled in parallel.

“In this case, the extension of the fabric is the same as that of the individual threads. But what happens is that the force developed is much higher when the threads are connected in parallel in the weave,” said Nils-Krister Persson of the Swedish School of Textiles at the University of Borås for ResearchGate.

The strong and flexible textile could be sewn into parts of clothing, like the sleeve tights, to made movement easier, i.e. use less energy. Right now, some people with motor disabilities use exoskeletons powered by motors or pressurized air to move about but these can cost $50,000 onward.

“Enormous and impressive advances have been made in the development of exoskeletons, which now enable people with disabilities to walk again. But the existing technology looks like rigid robotic suits. It is our dream to create exoskeletons that are similar to items of clothing, such as “running tights” that you can wear under your normal clothes. Such device could make it easier for older persons and those with impaired mobility to walk,” Jager said in a statement for the press.

That’s not to say that the muscle-like fiber made by the Swedish researchers can come close to exoskeleton practicality. The fiber was used to move a LEGO lever and lift a two-gram weight when an electrical current was passed through it but you’d need to do far more than that for it to be functional. There are also a couple of other limitations that right now make the fiber rather impractical, like the fact that it requires an electrolyte to actuate the artificial muscles. The researchers hope to make it work using only air instead.

Even so, this is some exciting research and might one day develop into a much more promising technology.

“I hope that this work will inspire others to look into the possibilities of textile technology,” says Jager. “My collaborators have taught me that textiles, ubiquitous as they are, can truly be high-tech technology.”

Bendy artificial muscle is made of pure nylon, still stronger than you

An MIT breakthrough allows engineers to create artificial muscles that bend by simply heating nylon fibers.

Image credits Unspalsh / Pexels.

Artificial muscles are just what they sound like — man-made materials that can contract and expand similarly to what our own biological sort can do. Coming up with a way of cheaply mass-producing artificial muscles with full motion could have enormous potential, revolutionizing the way we think about anything from robotics to clothes.

One of the most accessible materials which has shown promise in this field is nylon. Previous work has resulted in twisted-nylon filaments that could mimic linear muscle activity, which actually turned out to be more efficient than their natural counterparts. They could extend and retract further, store and release more energy. But a similar system that could produce bending motions turned out far more difficult to recreate until now. There are some materials that can do the job, but they (mostly) use up exotic materials which are very difficult to obtain, and thus very expensive.

That might be changed by Seyed Mirvakili, a doctoral candidate, and Ian Hunter, the George N. Hatsopoulos Professor in the Department of Mechanical Engineering, MIT. The two have developed one of the simplest and lowest-cost system for developing such muscles to date, resulting in materials that can reproduce a range of bending motions performed by biological tissues.

Their method relies the same property that makes highly-oriented nylon fibers ideal for liner muscles, called strain: when heated, “they shrink in length but expand in diameter,” Mirvakili says. Using it as-is to create bending muscles would require extra elements, such as a pulley and take-up reel, which would negatively impact the muscles‘ spacial efficiency, power, and production cost. But by pressing the fibers in specific shapes and then heating them, the team could directly harness this property without any extra parts.

“The cooling rate can be a limiting factor,” Mirvakili says. “But I realized it could be used to an advantage.”

By healing up only one side of the fiber, the strands can be made to contract faster than the heat can reach the other side, producing a bending motion in the fiber. The strands can maintain their performance for at least 100,000 bending cycles and can achieve at least 17 cycles per second.

“You need a combination of these properties,” he says: “high strain and low thermal conductivity.”

The team started with run-of-the-mill fishing line, then pressed it to progressively make its cross-section rectangular, then square. Selectively heating one side of the square caused the fiber to bend in that direction. By changing the direction of heating, the team could create complex motions in the strands, such as circles or figure-eights — but they’re confident that much more complex patterns can be achieved rather easily.

Nylon muscles

Fabrication steps from raw circular filament to a fully functional bending artificial muscle. From bottom to top: raw circular filament, a filament pressed in a rolling mill, one with a mask in the middle of the surface, then with added conductive ink. Finally, the mask is removed after the ink is dried (the sample on the top).
Image credits Felice Frankel, Seyed Mohammad Mirvakili, MIT.

The researchers tested a special conductive paint which they applied to the fibers with a special resin. When a voltage was applied to the material, it heated up the fiber directly under the paint, causing it to bend. But heat sources such as electrical resistance heating, chemical reactions, even lasers, can be used to heat the fibers and create motion.

Potential applications could include clothes that fit on any individual, or shoes that adjust their shape on each step. They could be used to create self-adjusting catheters and other biomedical devices. And, in the long run, they could be used to build vehicles that change shape for maximum performance, or sun-tracking solar panels, Hunter says. The possibilities are only limited by our imagination.

The full paper “Multidirectional Artificial Muscles from Nylon” has been published in the journal Advanced Materials.

Popeye gene mutations linked to heart and muscle conditions

Scientists from the University of Ferrara, Italy collaborating with the Beijing Genomics Institute have isolated a gene that, when mutated, causes muscle tissue to become significantly weakened and damaged. Their findings, published in The Journal of Clinical Investigation, show how the gene, dubbed Popeye domain containing-1, has a role in ‘gluing’ muscles cells together.

Zebrafish tail muscles with faulty Popeye gene (top) and healthy gene (below). Image via imperial

Zebrafish tail muscles with faulty Popeye gene (top) and
healthy gene (below).
Image via imperial

 

The two institutions pooled their efforts to study the genetic heritage of an Italian family who all suffer from muscular dystrophy. This progressive condition damages and weakens skeletal muscle tissue more and more with age, making movement and coordination near impossible for patients. The family is also plagued by a condition known as cardiac arrhythmia, that manifests as irregular and abnormal heart beat patters.

The Popeye group of genes were first identified 15 years ago by scientists from the Imperial College of London. Investigating on Zebrafish muscle tissue, they found that mutations of the gene affected both heart and skeletal muscle function — the gene regulates the production of a protein crucial in making muscle cells adhere to each other, allowing better performance by keeping them glued together and supporting each other.

Writing in the paper, Professor Thomas Brand said:

“This is the first example that this specific gene can cause both heart and muscle disease.”

The above image from the study shows the muscles in the tail of a Zebrafish with a mutated version of the gene, leading to damage in the tissue. The image below it shows a Zebrafish tail with a normal copy of the gene.

Although scientists have long known that muscular dystrophy is linked to heart conditions, they are still trying to find the genes that cause both conditions.

“From here we need to find out whether this gene causes the disorders in just this family, or whether it has wider implications for other patients,” explained Professor Thomas Brand, senior study author, from the National Heart and Lung Institute at Imperial.

onion muscle

Scientists make muscles out of gold plated onions

When it comes to artificial muscles, researchers at from National Taiwan University really know their onions. The team applied an uncanny design in which they layered gold atop the treated skin of onions. Once an electrical current was discharged, the “onion muscle” contracted and bent, just like the real thing. There’s a whole slew of possible applications for artificial muscles, from so-called “soft robotics” (flesh-like droids), to of course helping injured humans.

onion muscle

Image: Flickr // Onion Fights

Most artificial muscle models presented thus far were made from polymers, and unfortunately fail when it comes to replicating real muscle quality like staying soft and bendable even when contracting.

“There are artificial muscles developed using elastomers, shape memory alloys, piezoelectric composites, ion-conductive polymers and carbon nanotubes,” says Wen-Pin Shih of National Taiwan University in Taipei for ZME Science. “The driving mechanisms and functions are very diverse.”

Onion is not only a cheaper natural substitute to polymers, it’s actually far better for the task at hand. The team only used the epidermis of the onion, however – its skin. This thin film is both stretchy and responsive to electricity. The skin was then freeze-dried to remove any excess water, then bathed in dilute sulfuric acid to increase elasticity by removing the hemicellulose, a protein that makes the cell walls rigid. Gold was layered on both sides for increased electrical conductivity. Finally, when a current was transferred through the onion, it bent and stretched much like a muscle. What a tear jerker!

“We intentionally made the top and bottom electrodes a different thickness so that the cell stiffness becomes asymmetric from top to bottom,” said Shih.

Indeed, this way when a low voltage (0 to 50 volts) was applied the onion muscle expanded and flexed downwards, while a high voltage (50 to 1000 volts) caused the cells to contract and flex upwards. By carefully controlling the voltage, the team was able to grab a small cotton ball using the onion muscle.

Schematic details the process of transforming onion skin cells into muscles. Image: Shih Lab, National Taiwan University.

Schematic details the process of transforming onion skin cells into muscles. Image: Shih Lab, National Taiwan University.

The high voltage, however, makes it impracticable for use in mobile applications like tiny bots, which typically use small batteries. “We will have to understand the configuration and mechanical properties of the cell walls better to overcome this challenge,” Shih notes.

Also, another drawback of using vegetables in high tech devices is durability. Decay and water infiltration are two main issues that need to be highlighted, with this in mind. Shih already has a plan for this: applying a very thin fluoride layer to keep water out, while also retaining the bending/contracting ability. The onion muscles was reported in a paper published in  Applied Physics Letters.

Artificial muscle is quite the thing in research today. A while ago, ZME Science reported how University of Texas at Dallas researchers found a way to manufacture artificial muscle that is up to 100 times stronger than the flimsy tissue that makes up the human biceps. The material is made out of nylon fibers – the stuff fishnets are made of – that are tensed almost to the upper limit and thermal processed to retain a high energy density.

Schematic representation of a polymer gel whose chains are cross-linked using rotating molecular motors (the red and blue parts of the motor can turn relative to each other when provided with energy). Right: When exposed to light, the motors start to rotate, twisting the polymer chains and contracting the gel by as much as 80% of its initial volume: in this way, part of the light energy is stored as mechanical energy. © Gad Fuks / Nicolas Giuseppone / Mathieu Lejeune

Gel contracts like muscle and stores light energy

Researchers at the Université de Strasbourg  made a polymer gel that is able to contract similar to how a muscle concentrates motor proteins to elicit motion. The contraction occurs under the influence of light, but besides contraction, the gel also stores some of the absorbed light.

A gel battery

Schematic representation of a polymer gel whose chains are cross-linked using rotating molecular motors (the red and blue parts of the motor can turn relative to each other when provided with energy). Right: When exposed to light, the motors start to rotate, twisting the polymer chains and contracting the gel by as much as 80% of its initial volume: in this way, part of the light energy is stored as mechanical energy. © Gad Fuks / Nicolas Giuseppone / Mathieu Lejeune

Schematic representation of a polymer gel whose chains are cross-linked using rotating molecular motors (the red and blue parts of the motor can turn relative to each other when provided with energy). Right: When exposed to light, the motors start to rotate, twisting the polymer chains and contracting the gel by as much as 80% of its initial volume: in this way, part of the light energy is stored as mechanical energy. © Gad Fuks / Nicolas Giuseppone / Mathieu Lejeune

Muscles, like most living systems, perform functions at the macroscale through the collective molecular motion at the nanoscale. These molecular motors are highly complex protein assemblies that can produce work by consuming energy. For example, many protein-based molecular motors harness the chemical free energy released by the hydrolysis of ATP in order to perform mechanical work. Basically, these underlie all motion processes in biological systems (like the human body), but also work to copy DNA and synthesize proteins.

Individually, these molecular motors operate over an extremely short distance in the nano range. Yet, when millions join up they behave in a coordinate matter and collectively produce effects at the macroscale.

For a long while, scientists have been trying to mimic this behavior and produce artificial molecular motors. Undeterred by previous failed attempts, researchers at the Institut Charles Sadron, led by Nicolas Giuseppone, professor at the Université de Strasbourg, replaced a gel’s reticulation points, which cross-link the polymer chains to each other, by rotating molecular motors made up of two parts that can turn relative to each other when provided with energy. When light was shone, the artificial motors activated twisting the polymer chains in the gel, causing it to contract.

Just as in living systems, the motors consume energy in order to produce continuous motion. However, this light energy is not totally dissipated: it is turned into mechanical energy through the twisting of the polymer chains, and stored in the gel. But it’s not very much for now. According to the paper published in Nature Nanotechnology, the gel only converts 0.15% of the incoming energy into mechanical energy via contractions.

The plan is to exploit the gel somehow by finding a feasible way to extract the stored energy. Something like solar powered gel batteries, but it’s still very early to tell how this research will fair in the future.

Strands of engineered muscle fiber, stained different colors to observe growth after implantation into a mouse. Duke University

Most advanced lab-grown muscle can self-heal, mouse implant shows

Strands of engineered muscle fiber, stained different colors to observe growth after implantation into a mouse. Duke University

Strands of engineered muscle fiber, stained different colors to observe growth after implantation into a mouse. Duke University

Heralded as one of the biggest advances in the field, scientists at Duke University have engineered muscle tissue that is up to ten times stronger than anything previously achieved. The muscle can contract similarly to native neonatal skeleton muscle and, most importantly, it demonstrates self-healing ability – again, just like the real thing. To demonstrate their work, the researchers also implanted the muscles in bionic mice and followed the muscle fibers as they grew through a window on the back of the living animal.

“The muscle we have made represents an important advance for the field,” said Nenad Bursac, associate professor of biomedical engineering at Duke. “It’s the first time engineered muscle has been created that contracts as strongly as native neonatal skeletal muscle.”

Artificially creating muscles is a great challenge, but if muscle implants are demonstrated in humans, then a slew of injuries or degenerative muscle diseases could be addressed therapeutically. The team led by Bursac found that the two most important aspects that need to be considered when engineering muscles are the contractile muscle fibers and a pool of muscle stem cells, known as satellite cells.

[ALSO READ] Synthetic muscle made from nylon is 100 times stronger than human muscle

Self-healing muscle grown in a lab

The latter is of significant important in all muscle carrying organisms. Your muscles has many, many such satellite cells layered around them, waiting in standby until they’re efforts are required. For instance, when an injury occurs to the muscle, like those following a car accident or even a hefty workout, the satellite cells activate and begin the regeneration process.

Destruction and subsequent recovery of engineered muscle fibers that had been exposed to a toxin found in snake venom (credit: Duke University)

Destruction and subsequent recovery of engineered muscle fibers that had been exposed to a toxin found in snake venom (credit: Duke University)

The key to the team’s success was successfully creating the microenvironments—called niches—where these stem cells await their call to duty.

“Simply implanting satellite cells or less-developed muscle doesn’t work as well,” said graduate student Mark Juhas. “The well-developed muscle we made provides niches for satellite cells to live in, and, when needed, to restore the robust musculature and its function.”

First, the researchers ran a series of trials on the muscles in the lab, submitting it to electrical impulses. The muscle contracted showing strength 10 times greater than anything demonstrated in a lab previously. Then, the muscle was damaged using snake venom and satellite cells activated, proving their environment can help the muscle regenerate.

A window peering into progress

Veins slowly growing on implanted muscle in mouse host. Photo: Duke University

Veins slowly growing on implanted muscle in mouse host. Photo: Duke University

Then followed the trial on mice. The researchers inserted their lab-grown muscle into a chamber in the back of mice and implanted a window to follow progress. The evolution turned out to be spectacular, as the muscles proved to grow stronger as the days and weeks passed by. To make things easier, the muscle was genetically engineered to express fluorescent flashes during calcium spikes—which cause muscle to contract.

“We could see and measure in real time how blood vessels grew into the implanted muscle fibers, maturing toward equaling the strength of its native counterpart,” said Juhas.

The ultimate test will follow next, as the researchers need to investigate whether or not the biomimetic muscle can be used to repair actual muscle injuries and disease in humans.

“A number of researchers have ‘grown’ muscles in the laboratory and shown that they can behave in similar ways to that seen in the human body,” said Mark Lewis, an expert in skeletal muscle tissue engineering at Loughborough University, who wasn’t involved in the study. “However, transplantation of these grown muscles into a living creature, which continue to function as if they were native muscle has been taken to the next level by the current work.”

The findings were reported in the journal PNAS.

Photograph comparing muscles made by coiling (from left to right) 150 μm, 280 μm, 860 μm and 2.45 mm nylon 6 monofilament fibers. Photo: Science

Synthetic muscle made from nylon is 100 times stronger than human muscle

Sometimes, I come across stories or various research that make me wonder “why the heck hasn’t anyone else thought of this before?” We should be grateful, nevertheless, that researchers from University of Texas at Dallas have found a way to manufacture artificial muscle that is up to 100 times stronger than the flimsy tissue that makes up the human biceps. The material is made out of nylon fibers – the stuff fishnets are made of – that are tensed almost to the upper limit and thermal processed to retain a high energy density.

Like very thin springs, the synthetic muscle is cheap, easy to make and durable. Of course it has some drawbacks, however the researchers envision its introduction in the industry extremely fast considering the facts. Applications include artificial muscles for robots, exoskeleton suits, or automatically heat-regulated window shutters and ventilation systems.

Photograph comparing muscles made by coiling (from left to right) 150 μm, 280 μm, 860 μm and 2.45 mm nylon 6 monofilament fibers. Photo: Science

Photograph comparing muscles made by coiling (from left to right) 150 μm, 280 μm, 860 μm and 2.45 mm nylon 6 monofilament fibers. Photo: Science

The process through which the synthetic sinew is coiled is quite trivially simple. Basically, it boils down to making sure you apply the right tension and weight to the thread when twisting it. Actually, according to the scientists involved in the work, similar nylon coils like the ones they produced can be made by regular people at home.

Nylon or polyethylene gets twisted under high tension over and over again until it reaches a certain strain threshold. Once the plastic can’t twist any more, it starts to coil up on itself like a curled telephone cord. The coil is then thermally treated so it gets locked in place; along with energy stored in the coil. When the resulting coil is heated, it begins to untwist, but in the process the whole whole material begins to compress.

“At first it seems confusing, but you can think of it kind of like a Chinese finger-trap,” says Ray Baughman, a materials scientist with the team. “Expanding the volume of the finger-trap, or heating the coil, actually makes the device shorten.”

By braiding and twisting different threads together and coiling them in different ways, you can end up with different kinds of variations in muscle strength, depending on the kind of application you’re looking for. Also, by blending in conductive wire or wrapping the muscle with a light-absorbing coating, the researchers can control the muscles’ movements with electricity and light instead of direct heat.

Photo: University of Texas at Dallas.

Photo: University of Texas at Dallas.

At the moment, the nylon artificial muscle isn’t all that efficient. While work is presently underway to solve inefficiency issues, by itself, even in its current form, this research is extremely impressive and will most likely get used in real-world applications real soon. It also is a great example of what you can achieve with readily available materials and technology just by applying novel tricks and strategies.

You can find out more in the paper published just today in the journal Science.

Why men have bigger noses than women

  • Men have noses 10 cm longer than women (on average), even with the same body size
  • This happens because men have more muscle tissue, which needs an extra oxygen intake
  • This change starts happening during puberty

Human noses come in all shapes and sizes, but despite that, generally speaking, men noses are significantly larger than female noses, and apparently, no one really tried to understand why that happens until now.

Image via the College of Dentistry.

Image via the College of Dentistry.

A new study from the University of Iowa concluded that men’s noses are about 10 percent larger than female noses, on average, in populations of European descent. The size difference, they believe, comes from the sexes different builds and energy requirements – males in general have more lean muscle mass, which requires more oxygen for muscle tissue growth and maintenance, and therefore they require larger oxygen intakes. Larger noses mean more oxygen can be breathed in and transported wherever it is needed in the body through blood.

Researchers note that this change in nose size starts to happen around the age of 11, often when puberty starts. Physiologically speaking, men start developing more lean mass at that time, while women start to develop more fat mass (breasts are largely fatty mass).

“This relationship has been discussed in the literature, but this is the first study to examine how the size of the nose relates to body size in males and females in a longitudinal study,” says Nathan Holton, assistant professor in the UI College of Dentistry and lead author of the paper, published in the American Journal of Physical Anthropology. “We have shown that as body size increases in males and females during growth, males exhibit a disproportionate increase in nasal size. This follows the same pattern as energetic variables such as oxygenate consumption, basal metabolic rate and daily energy requirements during growth.”

This research also goes to show why we have smaller noses than ancient human-like populations – such as the Neanderthals and Denisovans, for example. The reason, the researchers believe, is because they had a larger muscle mass, and thus needed more oxygen to sustain it. We have, by comparison, smaller muscle masses, and therefore, we can get away with smaller noses.

“So, in humans, the nose can become small, because our bodies have smaller oxygen requirements than we see in archaic humans,” Holton says, noting also that the rib cages and lungs are smaller in modern humans, reinforcing the idea that we don’t need as much oxygen to feed our frames as our ancestors. “This all tells us physiologically how modern humans have changed from their ancestors.”

So it’s all about the muscle – this is, from an oxygenation point of view, more “expensive” tissue than fat.

“So, in that sense, we can think of it as being independent of the skull, and more closely tied with non-cranial aspects of anatomy,” Holton says.

Journal Reference:

  1. Nathan E. Holton, Todd R. Yokley, Andrew W. Froehle, Thomas E. Southard. Ontogenetic scaling of the human nose in a longitudinal sample: Implications for genusHomofacial evolutionAmerican Journal of Physical Anthropology, 2013; DOI: 10.1002/ajpa.22402

Papuan weevils have screw-in legs

Long before humans were even thinking about developing the nut and bolt mechanism for screwing one thing to another, mother nature had it all planned and implemented, in this weevil from Papua which attaches their legs to their bodies instead of the old fashion ball-and-socket joint.

Weevils in Papua

Weevils are beetles from the Curculionoidea superfamily, a large and extended family, with over 60.000 species. Due to this fact, they are found almost anywhere in the world, including Papua New Guinea, a country in Oceania, near Australia.

Scientists from Institute for Synchrotron Radiation at the Karlsruhe Institute of Technology (ANKA) and the State Museum of Natural History in Karlsruhe in Germany, led by Thomas van der Kamp, have been studying Trigonopterus, a genus of 90 described species, observing and analyzing computed tomography (CT) scans of the Papuan weevil Trigonopterus oblongus. They discovered that the top pair of the beetle’s legs are attached in an extremely uncommon way via the trochanter, which screws into another small body part called the coxa, the equivalent of a hip.

Muscles and joints

The inside of coxa and external surface of the trochanter features a mechanism familiar to any mechanic working with nuts and bolts. The trochanter covers around 410 degrees or more than a complete rotation, while the internal threads on the coxa cover 345 degrees.

The muscles turn the legs on the screw threads, an arrangement that allows the weevils to twist their hind and middle legs through 130 degrees, and their front legs through 90 degrees. The joint is more difficult to dislocate than a ball-and-socket joint.
Van der Kamp then examined the legs of 15 more weevil species from different families to see if the same arrangement was used and discovered they did have a nut and bolt system like T. oblongus. The researchers suggested that “it’s a safe bet that all weevils have it.”

Via physorg